marine wbp grade types plywood test is with boiled - boil water proof glue used for boats making- what grade
Marine Grade plywood
Plywood is a wood product made out of thin layers of wood. Depends on thickness no of plies may be increased. Various types of grades are there in plywood.Marine grade plywood is one among them. To understand about this marine grade plywood , we must know some of the basic things about the plywood.
Thin layers of wood sheets bonded together using thermosetting resin based glues. There are various types glues available. The WBP grade glue is used for making the marine grade plywood. WBP means weather and boil proof. Plywood made out of this type of glue should withstand boiling water test. So, to test the plywood , a section of plywood is cut and put into boiling water for 72 hours. If the plywood is not delaminating means it passed the test indirectly the glue is WBP grade.
The glue used for WBP grade is either phenol formaldehyde or even higher grade melamine also. But for exposed condition Phenol formaldehyde is preferred.
Selection of thin layers of wood ,that is, veneers are important in making the marine grade plywood. Both the face side and core veneers should not have knot holes , splits, and too many joints. Discoloured veneeers are allowed to some extent. All type of rotary peeled veneers , sliced veneers are used for making marine grade plywood. Some of species used as faces are teak , merandi, mahogany, and gurjan. Mostly hardwood species are used in making marine grade plywood.
Marine grade plywood withstand against boiling water, cold water test and steam and dry heat test. This type of plywood should pass mycological test , against the fungal attack. Every country has its own standard to test this type of marine grade plywood.
In some cases to avoid micro organisms attacks on this plywood , it is treated with cca (copper chrome arsenic compound) solution. Pressure impregnation methods used to treat marine grade plywood.
While using the marine grade plywood for making boats ,seal all edges and faces to keep water penetrating into the plywood. Use epoxy clear coat minimum 3 to 4 times at edges. For the face side you must coat with epoxy clear atleast two times. Then use exterior grade varnish atleast 8coats for edges, 4 coats for faces.
Marine grade plywood also used for furnitures making, interior partition also.